java - doInBackground 卡住了

Question

我正在尝试创建一个使用多个端口的服务器，以便可以轻松发送和接收不同的数据和信息，但在我的 doInBackground 方法中，我的代码卡在了 socket.receive 上，这是我的代码

while( run )
    {
        //GameServerID
        try
        {
            if(gameServerID == null)
            {
                gameServerID = new DatagramSocket( portID );
            }
            //try to receive data
            byte[] buf = new byte[256];
            DatagramPacket packet = new DatagramPacket( buf, buf.length );
            try
            {
                Log.d(TAG, "Wait for something to connect");
                gameServerID.receive( packet ); <--GETS STUCK HERE
            }
            catch (IOException e) 
            {
                Log.d(TAG, "Error with receiving data");
                e.printStackTrace();
            }
            String data = new String( buf, 0, packet.getLength() );
            Log.d(TAG, data);
            //Send out the ID to the client
            byte[] bufer = new byte[256];
            //Send a message "connect" to the host
            String msg = Integer.toString( players );
            players = players + 1;
            bufer = msg.getBytes();
            InetAddress address;
            //Default ip address of the host
            address = packet.getAddress();
            DatagramPacket p = new DatagramPacket( bufer, bufer.length , address, portID );
            //Send packet
            gameServerID.send( p );
            addresses.add( address );
        }
        catch (SocketException e) 
        {
            Log.d(TAG, "Error with socket");
            e.printStackTrace();
        } 
        //Listen for a client to connect
        catch (IOException e) 
        {
            Log.d(TAG, "Error with I/O");
            e.printStackTrace();
        }

        //GameServerPositions
        try
        {
            Log.d(TAG, "Run the gamePositions code");
            if(gamePositions == null)
            {
                gamePositions = new DatagramSocket( portPos );
            }
            //Receive position
            //try to receive data
            byte[] buf = new byte[256];
            DatagramPacket packet = new DatagramPacket( buf, buf.length );
            try
            {
                gamePositions.receive( packet );
            }
            catch (IOException e) 
            {
                Log.d(TAG, "Error with receiving data");
                e.printStackTrace();
            }
            String data = new String( buf, 0, packet.getLength() );
            Log.d(TAG, data);
            String[] pos = data.split(":");
            for(int i = 0;i<pos.length;i++)
            {
                Log.d(TAG, pos[i]);
            }
            xValues[ Integer.parseInt( pos[0] ) ] = Integer.parseInt( pos[1] );
            yValues[ Integer.parseInt( pos[0] ) ] = Integer.parseInt( pos[2] );
        }
        catch (SocketException e) 
        {
            Log.d(TAG, "Error with socket");
            e.printStackTrace();
        } 
        //Listen for a client to connect
        catch (IOException e) 
        {
            Log.d(TAG, "Error with I/O");
            e.printStackTrace();
        }

        //GameServerSendPos
        try
        {
            Log.d(TAG, "Run the gamePositionsSend code");
            String data = "";
            if( gameSendPos == null )
            {
                gameSendPos = new DatagramSocket( portSend );
            }

            //create the string ready to be sent out
            for(int i = 0; i < 8; i++)
            {
                if(xValues[i] >= 0)
                {
                    data += i + ":" + xValues[i] + ":" + yValues[i] + ":";
                }
            }

            byte[] bufer = new byte[256];
            bufer = data.getBytes();
            DatagramPacket p = null;

            for(int i = 0;i < addresses.size(); i++)
            {
                if( addresses.get(i) != null )
                {
                    p = new DatagramPacket( bufer, bufer.length , addresses.get(i), portSend );
                    gameSendPos.send( p );
                }
            }

        }
        catch (SocketException e) 
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
        catch (IOException e) 
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

我能做些什么来阻止它被卡住，或者在等了这么久之后，只是跳过它？只是为了了解更多信息，当第一个客户端连接时，代码工作正常，直到它再次到达顶部，然后 socket.received 就会卡住......

Canvas

更新

我已将代码更改为 3 个不同的类，我在服务器中启动它们，就像这样循环

while( run )
    {
        if(start == true)
        {
            gsID.doInBackground( );
            addresses = gsID.addresses;
            gsPos.addresses = addresses;
            gsPos.doInBackground( );
            gsSendPos.addresses = addresses;
            gsSendPos.positions = gsPos.positions;
            gsSendPos.doInBackground( );
            start = false;
        }
        else
        {
            addresses = gsID.addresses;
            gsPos.addresses = addresses;
            gsSendPos.addresses = addresses;
            gsSendPos.positions = gsPos.positions;
        }
    }

但它仍然再次卡在 gameServerID 接收方法上。

我刚刚将所有类更改为线程，并且效果更好，但是在 Android 4.0+ 的更高版本中，无法从 UI 使用线程，但我不确定如何从 UI 启动它们？

Answer 1

来自 DatagramSocket.receive 的 Javadoc :

This method blocks until a datagram is received

因此您的代码“卡住”了，因为它正在等待数据包到达。这意味着连接到此服务器/端口的客户端尚未发送另一个数据包，因此套接字在设计上处于阻塞状态。

传统上，如果您想同时监听多个端口，您有两个选择:

1. 在不同的线程上打开每个阻塞套接字(如果您同时拥有大量客户端，由于每个线程一个客户端，这将无法很好地扩展，但对于少量连接来说可以正常工作)
2. 使用 NIO，这是 Java 的非阻塞 IO